Conventionally, a graphical user interface (GUI) lets a user choose a desired button from among multiple buttons that are displayed on a screen. Such a GUI is disclosed in Japanese Patent Laid-Open No. 2011-51427 (JP '427). More practically, when the user performs a slide operation by sliding his/her fingertip on a touch pad, a pointer moves on a screen. The pointer may be positioned over one of the buttons, which may be provided as a selected button. When the pointer moves over such selected button, the selected button may be displayed in a manner different from the other buttons. In other words, the selected button may be emphasized by, for example, an added outline or a change of color, which is different from the other buttons. By displaying the selected button in a different manner, the GUI indicates that the button is in a selected state.
By having the selected button displayed in a manner different from the other buttons, the user can distinguish the button that is currently being selected at, even when an image of the pointer is not displayed on the screen. Accordingly, based on the slide operation of the user's fingertip on the touch pad, the button having the pointer changes, therefore, the emphasis placed on a selected button transitions across from one button to another in accordance with the slide operation on the touch pad.
However, the slide operation of the fingertip may not always trace an intended line (e.g., a straight line) in spite of the user's intention. That is, even when the user thinks that his/her hand or finger is moving in a straight line, the trace of the movement may actually be a curve. Such a curve may likely be drawn as a portion of a circle that has its center aligned with one and of the user's arm when the user's arm is on a structure close to the touch pad.
In such a case, when an image of the pointer is not displayed on the GUI screen, the user cannot recognize the curved movement of the fingertip, until the transition of the emphasis placed on a selected button moves in a different direction. For instance, the transition of the emphasis on the buttons moves along an intended direction from the start of the finger movement up to a middle of an intended course of movement, and then the transition of the emphasis suddenly goes in another direction, which is different from the user's intention's. Such change in direction may be caused by the curved trace of the fingertip.
The actual movement of the pointer gradually departs, which may be not recognized, from the intended direction during the movement. Therefore, even when the user intends to select one button at a far end of a row arrangement of buttons by the pointer from the other end of the row of buttons, the finger movement may start to select (i.e., emphasize) the buttons on a different row, if there are two or more rows of buttons. Thus, when the user sees such result based on the movement of his/her fingertip, the user may feel uncomfortable, or believe that something is wrong with the device or the user's operation.